Security systems are increasingly used to protect people and valuables against crime, fire and other occurrences. Present day security systems are typically controlled by a microprocessor to provide greater sophistication and enhanced flexibility. The control terminal for the security system typically includes a keypad and display under microprocessor control.
Unfortunately, the increased sophistication and flexibility of microprocessor controlled security systems has created added complexity for operation. This complexity is a source of user frustration. Even more importantly, complex operation may cause the user to trigger a false alarm, or the alarm may fail to detect an emergency because of a user error in arming the system.
The task of arming and disarming a security system illustrates these problems. To arm the system the user must typically depress a sequence of number keys constituting an authorization code, followed or preceded by depressing an "arm" key. To disarm the system the authorization code and a "disarm" key must be depressed in a predefined sequence. If the sequence is not correct, the alarm will not arm or disarm. As the number of detectors and the number of alarm types increase, arming and disarming the system for different situations requires the input of longer sequences of command keystrokes. Moreover, to reduce the number of keys at the keypad, each key typically has multiple labels to serve multiple functions. The user must interpret the labels to determine the function being served by the key at a particular point in time.